I like Hero, Echo, Bravery, and Reason; I'd probably use them as middles, although I'd probably use Hero as a first. I think all your GPs are okay as middles, except Pilot, which just reminds me of Pilot Inspektor.

My all time favourite GP is Sherlock, which I'd be willing to use as a middle IRL, if my (future) DH fully agrees, and really wants it. I'd use most of my GPs as middles, especially as some are names I like that are just way too popular. There are some (mn on-popular GPs) I'd consider as firsts; possibly Codetta and Euterpe.